title: Characterization of TNF receptor subtype expression and signaling on pulmonary endothelial cells in mice.
abstract: TNF plays a crucial role in the pathogenesis of acute lung injury. However, the expression profile of its two receptors, p55 and p75, on pulmonary endothelium and their influence on TNF signaling during lung microvascular inflammation remain uncertain. Using flow cytometry, we characterized the expression profile of TNF receptors on the surface of freshly harvested pulmonary endothelial cells (PECs) from mice and found expression of both receptors with dominance of p55. To investigate the impact of stimulating individual TNF receptors, we treated wild-type and TNF receptor knockout mice with intravenous TNF and determined surface expression of adhesion molecules (E-selectin, VCAM-1, ICAM-1) on PECs by flow cytometry. TNF-induced upregulation of all adhesion molecules was substantially attenuated by absence of p55, whereas lack of p75 had a similar but smaller effect that varied between adhesion molecules. Selective blockade of individual TNF receptors by specific antibodies in wild-type primary PEC culture confirmed that the in vivo findings were due to direct effects of TNF receptor inhibition on endothelium and not other cells (e.g., circulating leukocytes). Finally, we found that PEC surface expression of p55 dramatically decreased in the early stages of endotoxemia following intravenous LPS, while no change in p75 expression was detected. These data demonstrate a crucial in vivo role of p55 and an auxiliary role of p75 in TNF-mediated adhesion molecule upregulation on PECs. It is possible that the importance of the individual receptors varies at different stages of pulmonary microvascular inflammation following changes in their relative expression.
authors.affiliation: Section of Anaesthetics, Pain Medicine and Intensive Care, Faculty of Medicine, Imperial College London, Chelsea and Westminster Hospital, London, United Kingdom.
authors.forename: Szabolcs
authors.initials: S
authors.lastname: Bertok
authors.forename: Michael R
authors.initials: MR
authors.lastname: Wilson
authors.forename: Anthony D
authors.initials: AD
authors.lastname: Dorr
authors.forename: Justina O
authors.initials: JO
authors.lastname: Dokpesi
authors.forename: Kieran P
authors.initials: KP
authors.lastname: O'Dea
authors.forename: Nandor
authors.initials: N
authors.lastname: Marczin
authors.forename: Masao
authors.initials: M
authors.lastname: Takata
mesh_terms: D000818:Animals; D019040:E-Selectin / Q000378:metabolism; D042783:Endothelial Cells / Q000378:metabolism*; D019446:Endotoxemia / Q000503:physiopathology; D018799:Intercellular Adhesion Molecule-1 / Q000096:biosynthesis; D008168:Lung / Q000502:physiology*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D011014:Pneumonia / Q000503:physiopathology; D047888:Receptors, Tumor Necrosis Factor, Type I / Q000378:metabolism*; D047889:Receptors, Tumor Necrosis Factor, Type II / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology*; D053319:Tumor Necrosis Factor Decoy Receptors / Q000378:metabolism*; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology; D015854:Up-Regulation; D019010:Vascular Cell Adhesion Molecule-1 / Q000096:biosynthesis
chemical_list: D019040:E-Selectin; D047888:Receptors, Tumor Necrosis Factor, Type I; D047889:Receptors, Tumor Necrosis Factor, Type II; D053319:Tumor Necrosis Factor Decoy Receptors; D014409:Tumor Necrosis Factor-alpha; D019010:Vascular Cell Adhesion Molecule-1; D018799:Intercellular Adhesion Molecule-1; C069521:recombinant human tumor necrosis factor-binding protein-1